duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
Xeroderma can be caused by a deficiency of vitamin A, vitamin D, systemic illness, severe sunburn, or some medication. Xeroderma can be caused by choline inhibitors. Detergents such as washing powder and dishwashing liquid can cause xeroderma.